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-   -   chassis ideas swerve (http://www.chiefdelphi.com/forums/showthread.php?t=95080)

Mark Sheridan 07-05-2011 16:22

Re: chassis ideas swerve
 
Quote:

Originally Posted by rocknthehawk (Post 1059965)
Mark, could you explain why they would need to stop to rotate? From watching their matches on Curie, I never saw them really stop moving.

To rotate their robot about its central vertical axis, they set each wheel to a 45 degree angle. I don't think they come to a dead stop before they start rotating. The nature of the turning procedure forces the robot to stop moving in the X and Y plane.

In this thread, I asked them to post more pictures of their 2010 robot.

http://www.chiefdelphi.com/forums/sh...ad.php?t=84838


Essential when rotating clockwise, let's say the right side drives forward and the left side reverses. Because the pivot action of the drive modules are actually connected front left to back right and vice versa, each sets rotate in opposite directions. Therefore the right side modules are actually facing opposition directions when rotating despite being driven from the same drive gearbox.

I hope this explains it, I finding hard to describe the motion. I have also observed that they engage the rotate motion very quickly and almost seamless with their driving. Perhaps this is due to their fast gearing in both drive and pivot.

Our team is also looking at 1717's drive train for next year, I think we will CAD it before we start asking ourselves if we actually have resources to pull it off. It would be competing against a new 6 wheel drive concept that emphasis on durability and ease of repair.

staplemonx 07-05-2011 18:13

Re: chassis ideas swerve
 
Quote:

Originally Posted by Mark Sheridan (Post 1059994)
To rotate their robot about its central vertical axis, they set each wheel to a 45 degree angle. I don't think they come to a dead stop before they start rotating. The nature of the turning procedure forces the robot to stop moving in the X and Y plane.

In this thread, I asked them to post more pictures of their 2010 robot.

http://www.chiefdelphi.com/forums/sh...ad.php?t=84838


Essential when rotating clockwise, let's say the right side drives forward and the left side reverses. Because the pivot action of the drive modules are actually connected front left to back right and vice versa, each sets rotate in opposite directions. Therefore the right side modules are actually facing opposition directions when rotating despite being driven from the same drive gearbox.

I hope this explains it, I finding hard to describe the motion. I have also observed that they engage the rotate motion very quickly and almost seamless with their driving. Perhaps this is due to their fast gearing in both drive and pivot.

Our team is also looking at 1717's drive train for next year, I think we will CAD it before we start asking ourselves if we actually have resources to pull it off. It would be competing against a new 6 wheel drive concept that emphasis on durability and ease of repair.

I follow you. To minimize the number od drive motors they crosslinked the drives as opposed to linking two wheels on one side so that they could rotate around center. 2 ways around this are 4 drive motors or a tank style turn with side wheels linked when you are ready to rotate.

That complicates things a bit. Now i could see why this drive gets heavy.

Going back to my incorect observation about pnuematic motors. Has anyone ever used them to control low torque rotation applications. This could be a way to have 4 individual drive motors while keeping the weight down.

Thanks

Siri 08-05-2011 06:51

Re: chassis ideas swerve
 
As to the banebots vs. Window motors, we've actually used both to steer our swerves (windows in 2010, Banebots in 2011). We had a few problems with both, but the Banebots definitely served us better.

With the Window motors, running 1 per wheel module (#35 chain, 15T to 15T), we suffered from their incompatibility with Jags until we removed the locking pins. If you do this from the start (and personally, I'd avoid Jags unless you're CANing), you might be fine.

With the Banebots (RS-540s, 256:1 planetary gearbox), we never had a problem with the motor, but the gearboxes loosened up sometimes. This was likely simply a product of our mounting, since we stole 2 of the attachment points to mount it to the pivot. Great motors, but it's hard to give them up to the drivetrain in some cases.

staplemonx 10-05-2011 16:27

Re: chassis ideas swerve
 
2 Attachment(s)
Here is an updated model. Based on ththe comments from this thread and http://www.chiefdelphi.com/forums/sh...threadid=95088 i am going to create to more concepts. I will also incorporate the banebot motors into one of the concepts.

Mark Sheridan 13-05-2011 01:34

Re: chassis ideas swerve
 
Quote:

Originally Posted by staplemonx (Post 1060014)
Going back to my incorect observation about pnuematic motors. Has anyone ever used them to control low torque rotation applications. This could be a way to have 4 individual drive motors while keeping the weight down.

Well I am no expert at pneumatic motors.

I have contemplated using pneumatic motors since FIRST has open up the pneumatic rules. They appear to be not used for precision motion. Pneumatic valves, simply can't move fast enough.

If you found a pneumatic motor small enough to use on a first robot, perhaps it would be better to replace motors elsewhere so that you can use extra motors on the drivetrain. Maybe, rework a pneumatic screwdriver or grinder? That would make a pretty funny roller claw.


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